diff --git a/pkgs/development/python-modules/tensorflow/bin.nix b/pkgs/development/python-modules/tensorflow/bin.nix
index aae4406d0d79..6d4df4eb2c8e 100644
--- a/pkgs/development/python-modules/tensorflow/bin.nix
+++ b/pkgs/development/python-modules/tensorflow/bin.nix
@@ -20,8 +20,8 @@
 , tensorflow-estimator_2
 , tensorflow-tensorboard_2
 , cudaSupport ? false
-, cudatoolkit ? null
-, cudnn ? null
+, cudatoolkit
+, cudnn
 , zlib
 , python
 , keras-applications
@@ -37,9 +37,6 @@
 # - the source build doesn't work on Darwin.
 # - the source build is currently brittle and not easy to maintain
 
-assert cudaSupport -> cudatoolkit != null
-                   && cudnn != null;
-
 # unsupported combination
 assert ! (stdenv.isDarwin && cudaSupport);